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Structure of a prehandover mammalian ribosomal SRP·SRP receptor targeting complex.

ABSTRACT: Signal recognition particle (SRP) targets proteins to the endoplasmic reticulum (ER). SRP recognizes the ribosome synthesizing a signal sequence and delivers it to the SRP receptor (SR) on the ER membrane followed by the transfer of the signal sequence to the translocon. Here, we present the cryo-electron microscopy structure of the mammalian translating ribosome in complex with SRP and SR in a conformation preceding signal sequence handover. The structure visualizes all eukaryotic-specific SRP and SR proteins and reveals their roles in stabilizing this conformation by forming a large protein assembly at the distal site of SRP RNA. We provide biochemical evidence that the guanosine triphosphate hydrolysis of SRP·SR is delayed at this stage, possibly to provide a time window for signal sequence handover to the translocon.

SUBMITTER: Kobayashi K

PROVIDER: S-EPMC6309883 | biostudies-literature | 2018 Apr

REPOSITORIES: biostudies-literature

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Structure of a prehandover mammalian ribosomal SRP·SRP receptor targeting complex.

Kobayashi Kan K Jomaa Ahmad A Jomaa Ahmad A Lee Jae Ho JH Chandrasekar Sowmya S Boehringer Daniel D Shan Shu-Ou SO Ban Nenad N

Science (New York, N.Y.) 20180322 6386

Signal recognition particle (SRP) targets proteins to the endoplasmic reticulum (ER). SRP recognizes the ribosome synthesizing a signal sequence and delivers it to the SRP receptor (SR) on the ER membrane followed by the transfer of the signal sequence to the translocon. Here, we present the cryo-electron microscopy structure of the mammalian translating ribosome in complex with SRP and SR in a conformation preceding signal sequence handover. The structure visualizes all eukaryotic-specific SRP ...[more]

PMID: 29567807

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